Skip to main content
Login | Suomeksi | På svenska | In English

Browsing by Subject "laatuarvot"

Sort by: Order: Results:

  • Fontell-Seppelin, Laura (2020)
    According to The Finnish Act on Water Resource Management, the ecological status of Finnish streams and lakes have to be monitored and assessed based on the severity of human impact on biota. The ecological assessment of freshwaters is based on comparing the impacted ecosystems with those freshwater ecosystems of a nearly intact state. The Finnish Act on Water Resource Management is based on the European Union Water Framework Directive, or WFD. Macrophytes (aquatic bryophytes, macroalgae, and vascular plants) are used as an element in freshwater assessment. In Finland, the used of macrophytes have been long established along with other organism groups in ecological assessment of lakes, but macrophytes have not yet been used extensively in ecological assessment of rivers. A rough method has been developed, but further study and improvement needs to be made before reliable ecological assessments using river macrophytes can be done. Currently, there is a great need for a uniform method for river assessment using macrophytes. In Finland, the ecological state of freshwaters is classified by using biological metrics based on the abundance and variety of different organism groups. The biological metrics are converted to a scale of 0-1 into a so-called Ecological Quality Ratio (EQR) in order to be able to compare their results. Suitable biological metrics have been studied in Finland, and so far, the Percent Model Affinity (PMA) and Observed-to-Expected-taxa index (O/E-taxa index) have proven to be promising. Both metrics have been observed to explain human impact in the catchment and changes in water quality. These metrics are hence used in this thesis. The variety and abundance of freshwater macrophytes was studied according to the rough method developed at the Finnish Environment Institute (SYKE) in 2008. In this thesis, the objective was to study how the results of the biological metrics varied between different river parts of Mätäjoki. The EQR and biological metrics results obtained earlier from diatoms and benthic invertebrates were also compared with the results obtained with macrophytes in the same river parts. A possible link to the results of the River Habitat Survey (RHS) and riverbank vegetation was also studied. The biological metrics used in this thesis are based on using reference sites (sites in natural condition) to assess the ecological condition of the studied sites. Data collected for the MaaMet-survey by the Finnish Environment Institute formed the reference conditions. The reference sites included were as pristine as possible. The field method consisted of gathering macrophyte data from two 50-metre-long adjacent river parts: a riffle and a pool. A total of 18 rivers and pools were included, forming 9 river-pool pairs. The riverbank vegetation was studied on the banks of the pools. In this thesis, we observed significant variation in both the biological metrics results and EQR results. The results of the biological metrics were surprisingly low, indicating a possibly bad ecological condition. The mean of EQR results using combined data, bryophyte data and vascular plant data were found to be very similar. The EQR results using macrophyte data were considerably lower than the EQR results of the diatom and benthic invertebrate data. Macrophytes thus indicated a possibly inferior ecological state than diatoms and benthic invertebrates. The species richness of Mätäjoki was found to be considerably lower than that of the reference sites. The surprising results may indicate shortcomings in the rough river macrophyte method. The small size of the reference condition data and issues in the national Finnish river classification system may also be responsible for some of the results. Low EQR results, indicating low ecological state, may be a result from the impaired ecological state of Mätäjoki due to human impact. Moreover, the ecological assessment of urban rivers based on biota has in some studies produced unreliable results on other organism groups. The results show that biological metric values show a large variation between river parts. This must be taken into consideration in the development of the river macrophyte method and in choosing the sampling sites of studied rivers.